Flash memory devices have been recognized as an attractive non-volatile data storage option for mobile computers and smartphone devices because of their small size, light-weight, shock resistance, fast access speed, and low power consumption. It is anticipated that with further advances in flash memory technology, its popularity may rival or even outpace hard disks. However, due to the different construction of flash memory as compared with a hard disk device, there are special considerations that have to be addressed in order to take advantage of the flash memory device.
In a flash memory device, a write operation has to be preceded by an erase operation, which takes much longer than the write operation itself. Further, the smallest addressable unit for read and write operations is a page, but the smallest erasable unit is a block. This means that to even write a single byte of data into a flash memory requires the erase and restoration of a block of data. In the unexpected event of power loss after the data is erased but before the data is restored and written into the flash memory, data would be lost if no precaution has been taken to address this issue.
In some conventional flash memory devices, capacitive devices have been used to keep supplying power to the flash memory so that the write operation may be completed. Such implementations not only have large component costs, but may be inadequate as the completion time for the write operation is unpredictable. The power in the capacitive device may still be insufficient to complete the write.